1. Field
Aspects of the present invention relate to an apparatus detecting a position of a functional layer on an electrode, and more particularly, to an apparatus detecting the position of an electrode and capable of detecting a functional layer coated on an electrode disposed on a material.
2. Description of the Related Art
Recently, as developments and demands on a mobile technology increase, use of a secondary battery as an energy source is rapidly increasing. Therefore, research on a battery that may satisfy various performance requirements are being conducted. In particular, research is being conducted on a lithium secondary battery having high energy density, a stable discharge voltage and a high output.
In general, in a secondary battery, after an active material is coated on the surface of a collector to form a positive electrode and a negative electrode and a separator is interposed between the positive electrode and the negative electrode to form an electrode assembly, the electrode assembly is mounted in a cylindrical or polygonal metal can or a pouch type case made of an aluminum laminate sheet. A liquid electrolyte is injected into the electrode assembly or the electrode assembly is impregnated with the liquid electrolyte or a solid electrolyte is used to manufacture the secondary battery.
In order to improve thermal stability of the secondary battery, a functional layer is coated on an electrode plate which is coated on a material that is the collector. The functional layer is coated on to the electrode plate by a coater having the functional layer material in a slurry state before being coated. The functional layer is a semi-transparent white color in a slurry state and is coated on the electrode plate on the material in the form of a thin film according to a predetermined pattern. The functional layer is coated on the electrode plate at a thickness of 10 to 15 μm and is semi-transparent after being coated and before being dried.
The functional layer as described above should be coated on the electrode plate in a correct position. However, current pattern recognizing apparatuses do not distinguish the electrode plate from the functional layer disposed on the electrode plate. If the functional layer is not coated on the electrode plate in the correct position, a coating position defect occurs in a winding process and local pressure is applied to a part where the defect occurs and the shape of a battery cell is not uniform after the winding process. In addition, the part to which the local pressure is applied is not impregnated with the electrolyte and lithium ions do not smoothly move between the negative electrode and the positive electrode. Thus, if the functional layer is not coated in the correct position, the thermal stability of the battery, which is provided by the functional layer, is affected.
Therefore, an apparatus sensing whether a previously coated functional layer is coated in a correct position and without an error is beneficial in order to correctly sense and adjust a position of a subsequent functional layer to be coated after the previously coated functional layer is coated on the electrode plate.
In general, in the case of a laser sensor or an infrared ray sensor applied to a common pattern coating process, a previously coated functional layer formed with the semi-transparent slurry is not correctly sensed, and thus, an error in the position of the previously coated functional layer is not sensed. When quality of a functional layer coating becomes poor due to the above problems, the quality of a coated functional layer may not be managed because no feedback is transmitted to the functional layer coater.